Bug Description

Tried install twice. Manual partition setup using existing partitions for root and home-selecting format for both. After selecting the timezone, the "Who Are you?" panel appears and the installer crashes immediately.

Update: If I pause for a minute or so before proceeding to "Who are you panel?", the install proceeds without issue. Without the pause, maybe installer is attempting to write to drive that is not fully formatted?

* kde, gtk: Wait for both timezone and partman_commit before installing.
We were racing starting the installation with committing the partition
table changes, if you were fast enough at the timezone selection page.
What we need to do is wait until both timezone selection *and*
partman_commit have finished before.
This is a little bit delicate, because the user setup page, which comes
after the timezone page, writes to debconf and so we have to be careful
not to restart it after the user setup page is shown. We do that after
finishing timezone selection, since this writes to debconf. It is not
needed after partman_commit, because it only reads. (LP: #1798005)